1. Field of the Disclosure
The present disclosure relates to an acoustic signal detector.
2. Background of the Disclosure
A target detection technique in a marine detection research field may include an active acoustic signal detection technique using a principle that a signal is transmitted to a target and then the signal is returned to the original position by the target, a passive acoustic signal detection technique using a principle that an acoustic signal transmitted from a target is received for detection, etc.
According to the active acoustic signal detection technique, a target is detected by using a signal transmitted to the target which is silently moving in water, and then returned by the target. In this active acoustic signal detection technique, it is important to generate an acoustic signal of a high output so as to detect a remote underwater target.
In order to generate an acoustic signal of a high output, a plurality of acoustic sensors are preferably arranged rather than a single acoustic sensor is used. By arranging the plurality of acoustic sensors, a transmitting beam of a high output is formed based on an output sum of each acoustic sensor toward a specific direction. Here, the beam-forming may be implemented in various manners. Generally, directivity and an output are increased as the number of acoustic sensors is increased.
In order to detect an acoustic signal reflected by a target by the active acoustic signal detection technique, or an acoustic signal directly emitted from a target by the passive acoustic signal detection technique in a wide range of marine environments, a signal has to be received in various directions. In order to precisely detect a target by receiving a signal in a wide range of directions, a plurality of acoustic sensors are used to form a receiving beam thus to increase a receiving gain. And, a plurality of receiving beams with respect to a wide range of directions are generated to precisely obtain an azimuth.
In order to precisely generate a receiving beam, the number and arrangements of sensors are important. Here, the directional beams can be precisely generated as the number of sensors is increased.
Both in the active acoustic signal detection technique and the passive acoustic signal detection technique, it is important to arrange sensors.
However, the active acoustic signal detection technique has been developed with focusing on a high output of a transmitting signal, rather than focusing on arrangements of sensors. And, the passive acoustic signal detection technique has been developed with focusing on enhancing a passive detection function by generating precise directional beams with respect to a wide range of directions.
Especially, in case of a body of a moving object which moves at a high speed in water such as an underwater guided weapon, a front part of the body of the moving object is formed in a streamlined shape due to many problems including noise. This restriction in shape causes not only the number of sensors but also arrangements of sensors to be severely limited.
More concretely, in a condition of the streamlined shape, there is a problem in forming a transmitting beam of a high output due to a small number of sensors which can be arranged. Furthermore, even if sensors are arranged in a state that a front shape of a body of a moving object which moves at a high speed has been changed in order to form a transmitting beam of a high output, there is a limitation in detecting a target in a wide range of directions.